Chimeras are animals – or maybe humanoids4 – made up of parts of animals from different species.

They were originally mythical beasts (Wikipedia: Chimera), improbable amalgams of lion, goat and snake, though mules (Wikipedia: Mule, the off-spring of a male donkey and a female horse) are chimeras as the parents are of different species with different numbers of chromosomes.

The paper’s rhetorical question is rather ludicrous as there would never be any intention5 of engineering pigs with the attributes needed to qualify as a person, nor the need to do so even in the case of neural tissue (which would remain in the petri-dish6).

Whether such a beast – whether hybridised with a human or not – were to qualify as a person7 ought to be based on its cognitive capacities and not merely on its chromosomes.

It is possible that this topic might relate to transhumanism8. Rather than adding small quantities of human to pig, we might add quantities of animal to human. This would be the case in organ transplants – where an essentially normal organ is transplanted – but it might be the case that augmentative strategies could be adopted whereby humans are enhanced with bodily features (or, say, the physiological infrastructure) of animals, much as in the case of cyborgs9, but with organic rather than inorganic parts.

There is currently, not much of a categorised reading-list for this topic. A reading list (where not covered elsewhere) might start with the items below, and I’ll pursue references from the Stanford paper if necessary:-

Admittedly, "Ishiguro (Kazuo) - Never Let Me Go" considers the cloning of human beings so their organs can be harvested, but this is presumably because it is deemed to be the technologically simplest solution.